The first book to map William James’s preoccupation with medical ideas, concerns, and values across the breadth of his work. William James is known as a nineteenth-century philosopher, psychologist, and psychical researcher. Less well-known is how his interest in medicine influenced his life and work, driving his ambition to change the way American society conceived of itself in body, mind, and soul. William James, MD offers an account of the development and cultural significance of James’s ideas and works, and establishes, for the first time, the relevance of medical themes to his major lines of thought. James lived at a time when old assumptions about faith and the moral and religious possibilities for human worth and redemption were increasingly displaced by a concern with the medically “normal” and the perfectibility of the body. Woven into treatises that warned against humanity’s decline, these ideas were part of the eugenics movement and reflected a growing social stigma attached to illness and invalidism, a disturbing intellectual current in which James felt personally implicated. Most chronicles of James’s life have portrayed a distressed young man, who then endured a psychological or spiritual crisis to emerge as a mature thinker who threw off his pallor of mental sickness for good. In contrast, Emma K. Sutton draws on his personal correspondence, unpublished notebooks, and diaries to show that James considered himself a genuine invalid to the end of his days. Sutton makes the compelling case that his philosophizing was not an abstract occupation but an impassioned response to his own life experiences and challenges. To ignore the medical James is to misread James altogether.